Tool balancing means



April 17, 1934.

E. A. HALL TOOL BALANCING MEANS Filed Dec. 15

Ii g/aiiaiiu Llllll Patented Apr. 17, 1934 UNITED STATES PATENT OFFICE TOOL BALANCING MEANS a corporation of Ohio Application December 15, 1933, Serial No. 702,440

12 Claims.

This invention relates to balancing means for precision tools, and particularly for valve-seat grinders of the type which, when in use, are mounted on and rise from a pilot stem above the valve-seat.

In valve-seat grinders, it is extremely important to grind the seat as nearly true as possible. In fact, it is necessary at the present time to grind valve-seats within one one-thousandth of an inch of true in order for them to be acceptable to automobile manufacturers.

The object of my invention is the provision of simple and efiicient means for use particularly in connection with valve-seat grinders, and which is operable to effect a true balancing of the grinder on the centering pilot, or in other words, to counter-balance any unbalanced condition of the grinder by reason of its center of gravity being out of alignment with the longitudinal axis of the pilot.

The invention is fully described in the following specification, and while in its broader aspect it is capable of embodiment in various forms, one embodiment thereof is illustrated in the accompanying drawing, in which- Figure 1 is the side elevation of a grinder equipped with the balancing means and mounted in operative relation to the work, the latter being shown in fragmentary section, and Fig. 2 is a plan of the operating lever of the balancing means with the pressure rod attached thereto and in section.

In the drawing, 1 designates an engine cylinder having a valve-seat 2 therein, 3 a pilot mounted in the associated valve-stem guide and rising through and above the valve-seat concentrically thereof, and 4 avalve-seat grinder mounted on the pilot above the valve-seat in position for its grinding wheel 5 to have coaction with the seat, as well understood in the art. In the present instance, the grinder is provided with a manually adjustable rod 6, which rests at its lower end on the top of the pilot and serves in conjunction with the pilot as a support for the grinder and as a means for controlling the feed of the grinder to the work. Grinders of this character usually have their centers of gravity offset from the longitudinal axis of the pilot 3.

The balancing means, in its present embodiment, includes a hand-lever '7, which has one end forked and straddling a portion of the grinder body with its arms pivoted to the body in axial alignment, as at 7, to permit vertical rocking movements of the lever, and has its outer end forming a handle. The fulcrum 8 of the lever is preferably so positioned that its axis substantially intersects the longitudinal axis of the pilot 3 at right angles to the direction in which the center of gravity of the grinder is offset from the pilot axis. The lever 7, in the present instance, projects from the grinder body at the side thereof toward which its center of gravity is offset.

A rod 9 is pivoted at its lower end to the lever near the inner end of its handle portion and projects upward therefrom through guide lugs 10 on the grinder body by which it is guided for vertical reciprocatory movements.

A shoulder or stop 11 is provided on the rod 8 above the lower lug 10 in position to engage such lug and limit the lowering movements of the rod and lever when not being operated to balance the grinder.

A coiled expansion spring 12 is interposed between the stop 11 and upper lug 10 in opposed end thrust engagement therewith, thus tending to resist a raising of the lever handle, or, in other words, causing a raising of said handle to effect a compression of the spring 12 and a consequent yielding upward pressure on the adjacent side of the grinder to counterbalance any unbalanced condition of the grinder tending to cause it to tip in the direction of the applied pressure. It is preferable, in practice, to fixedly attach the stop 11 to the rod 9, so that its adjustment cannot easily be changed after leaving the factory.

A notch or other indicating mark 13 on the rod 9 registers with a mark or pointer 14 on the grinder body when the spring has been tensioned sufficiently by a raising of the lever handle to effect an accurate counterbalancing of any unbalanced condition of the grinder, thus providing visual means for indicating to the operator when a balance is obtained.

It is found, in practice, that a workman using a grinder equipped with my counterbalancing means can easily effect a grinding of valve-seats, or the like, to within one one-thousandth of an inch of true, whereas without such means it is practically impossible to obtain a seat within several thousandths of an inch of true.

It is apparent that in the use of a grinder equipped with my balancing means, the operator. during the grinding operation, applies sufficient upward pressure to the lever handle '7 to maintain the marks 13 and 14 on the rod 9 and grinder body 4, respectively, in register, thus overcoming to a nicety any predetermined unbalanced condition of the grinder, and avoiding the tendency of the grinder to grind the seat more on one side than the other, due to such condition.

I wish it understood that my invention is not limited to any specific construction, arrangement or form of the parts, as it is capable of embodiment in various forms without departing from the spirit of the claims.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent, is:

1. A valve-seat grinder having an attachment manually operable during a grinding operation to correct a predetermined unbalanced condition thereof.

2. In a valve-seat grinder, means having a yielding pressure connection therewith and manually operable during an operation of the grinder to correct a predetermined unbalanced condition thereof.

3. In an abrading tool, a manually operable control member, and yielding connection between said member and the tool for correcting a predetermined unbalanced condition of the latter when in use.

4. In combination, an abrading tool having a predetermined normally unbalanced condition when in use, and yielding means connected thereto and manually operable during use to correct said condition.

5. In combination, an abrading tool having a predetermined normally unbalanced condition when in use, a yielding pressure member attached thereto, and means manually operable to cause said member to apply a predetermined counterbalancing pressure to said tool when in use to substantially correct its unbalanced condition.

6. In combination, an abrading tool having a normally unbalanced condition when in use, a yielding pressure member attached thereto, and a lever fulcrumed to the tool and operable to cause said member to apply a predetermined counterbalancing pressure to said tool when in use to substantially correct its unbalanced condition.

7. In combination, a pilot, an abrading tool mounted on and centered with respect to the work by the pilot, said tool being normally unbalanced with respect to the, pilot, and yielding means manually operable during use of the tool to correct such unbalanced condition.

8. In combination, a pilot, an abrading tool mounted on and centered with respect to the work by the pilot, said tool having its center of gravity offset with respect to the pilot axis, and yielding means disposed at the same side of the pilot axis as the center of gravity of the tool and manually operable during use of the tool to correct the unbalanced condition.

9. In combination, a pilot, an abrading tool mounted on and centered with respect to the work by the pilot, said tool having a predetermined unbalanced condition with respect to the pilot, and spring pressure means attached to the tool and operable to apply a predetermined counterbalancing pressure thereto to correct its unbalanced condition, said means including a control member which is manually operable during use of the tool.

10. In combination, a pilot, an abrading tool mounted on and centered with respect to the work by the pilot, said tool being normally unbalanced with respect to the pilot, a lever fulcrumed to the tool, and means connecting the lever and tool and operable by a predetermined movement of the lever to correct the unbalanced condition of the tool.

11. In combination, a pilot, an abrading tool mounted on and centered with respect to the work by the pilot, said tool having its center of gravity offset from the pilot axis, and means disposed at said offset center of gravity side of the tool and manually operable to apply a predetermined yielding pressure to the tool to correct its unbalanced condition with respect to the pilot, said means including a reciprocally movable control member which is manually operable during use of the tool.

12. In combination, a pilot, an abrading tool mounted on and centered with respect to the work by the pilot, said tool being normally unbalanced with respect to the pilot, a rod attached to and guided for vertical reciprocatory movements by the tool, manual control means for reciprocating the rod, and means for applying a yielding counterbalancing pressure to the tool when the rod is raised a predetermined extent.

ERNEST A. HALL. 

